JSP file not working for Google App Engine with Eclipse Plugin
Java Run-time Environment is not enough for Google App Engine. You should add Java Development Kit (JDK latest version).
Open : Windows => Preferences => Installed JREs
Now You add JDK folder,
Click Add Button -> Choose Standard VM and Browse JDK Base Directory ( Example C:\Program Files\Java\JDK1.6.0_22)
Select JDK and Refresh the Project;